When a silver halide photographic material is exposed to light and then is subjected to a color-developing process, a developing agent, such as an aromatic primary amine derivative that has been oxidized with a silver halide, reacts with dye-forming couplers to form a color image. Generally, in this technique, the color reproduction method by the subtractive color process is often carried out, and in order to reproduce blue, green, and red, color images of yellow, magenta, and cyan, complementary respectively to blue, green, and red, are formed.
As cyan color image-forming couplers, phenols and naphthols are used in many cases. However, the preservability of color images obtained from phenols and naphthols that are conventionally used has some problems that remain unsolved. For example, color images obtained from 2-acylaminophenol cyan couplers described, for example, in U.S. Pat. Nos. 2,367,531, 2,369,929, 2,423,730, and 2,801,171, are generally poor in fastness to heat, color images obtained from 2,5-diacylaminophenol cyan couplers, described in U.S. Pat. No. 2,772,162 and 2,895,826, are generally poor in fastness to light, and 1-hydroxy-2-naphthamide cyan couplers are generally not adequate concerning both fastness to light and fastness to heat (particularly heat and humidity).
In order to overcome the defects of these cyan dye-forming couplers, for example, 5-hydroxy-6-acylaminocarbostyryl cyan couplers, described in U.S. Pat. Nos. 4,327,173 and 4,564,586, and 4-hydroxy-5-acylaminooxyindole couplers and 4-hydroxy-5-acylamino-2,3-dihydro-1,3-benzimidazol-2-one couplers, described in U.S. Pat. No. 4,430,423, are developed. These couplers are excellent concerning fastness to light and fastness to heat. Although these couplers are unique couplers having a hetero atom in the mother nucleus that will form a color, any of the rings having a dissociative group for color formation is equivalent to phenol.
Further, cyan dyes obtained from conventionally used phenols and naphthols have subsidiary absorption in the blue and green regions, and therefore are not preferable, particularly in view of the reproduction of green color, so that their improvement is desired.
On the other hand, concerning couplers that have a hetero atom introduced in a ring having a dissociative group, only 3-hydroxypyridine and 2,6-dihydroxypyridine are disclosed in U.S. Pat. No. 2,293,004. However, the absorption wavelength of the absorption obtained by 3-hydroxypyridine, described in tis U.S. Pat. No. 2,293,004, is extreme on the short wavelength side and the absorption peak is broad. Further, this 3-hydroxypyridine is soluble in water. Therefore, 3-hydroxypyridine cannot be used as a so-called cyan coupler
Further, although pyridine-type cyan couplers having a dissociative group in the 3-position are disclosed in EP No. 0333185, a more improved one is desired in view of color-forming properties.
On the other hand, in recent years, in view of environmental pollution and solution preparation, color developers free from benzyl alcohol have come to be used, but with rapid processing using such color developers there is a problem that adequate color density cannot be obtained with these cyan couplers, and therefore new couplers that overcome these problems are desired.